China's new fuel-efficiency rules bring the country roughly into line with similar regulations in Europe and the United States. That gives global automakers a further incentive to develop even more efficient cars, since they'll be required by the world's single largest auto market.

Pollution problems

Recently, record-breaking smog levels in some Chinese cities have posed a major hazard to health. People are frequently advised to stay indoors and avoid anything that may cause heavy breathing. High pollution levels have caused unrest and even sparked riots in certain parts of the country.

Much of the blame is laid on the country's reliance on coal power and coal-fired heaters, use of which rises over winter and traditionally leads to greater pollution.

The imposition of stricter standards will make life harder for some of the country's struggling domestic automakers.

Yale Zhang, head of Shanghai-based industry consultancy Automotive Foresight, says the new efficiency rules will be "tough for everyone, especially those small players as they will have to use more fuel-efficient engines and invest in hybrid technologies."

As well as cleaning up the country's vehicles, Chinese Premier Li Keqiang says the country will do more to curb China's increasing pollution problems.